1. Field of the Invention
The present invention relates to an image sensing apparatus and control method of the image sensing apparatus, particularly to a shutter control of an image sensing apparatus.
2. Description of the Related Art
Conventionally, an arrangement, which retains a shutter blade by a shutter latch mechanism after a charge operation of a shutter device is completed by a shutter charge mechanism, and stops the shutter charge mechanism in a travel prepared state in which the charged state by the shutter charge mechanism is released, is known. As another arrangement, after the charge operation by the shutter charge mechanism is completed, the shutter charge mechanism is stopped in the charged state to retain the shutter blade. Then, the shutter charge mechanism is shifted from the charged state to the travel prepared state interlockingly with a shutter release operation, thus attaining a shooting operation.
Japanese Patent Laid-Open No. 2000-089358 describes an arrangement which includes a mirror, stop, and unit for charging a shutter, and performs an exposure preparation operation without waiting for completion of the charge operation of the shutter when the charged states of the mirror and stop are detected in a continuous shooting mode. Japanese Patent No. 2765747 describes an arrangement that retains a latch lever by pressing it by a retaining lever against an armature after a shutter charge operation, and externally releases a body release lever that retains the retaining lever before shutter traveling. In this arrangement, the mirror is retracted to a position outside a shooting optical path, and the body release lever is released interlockingly with retraction of the mirror.
However, in the arrangement which stops the shutter charge mechanism in the travel prepared state in which the charged state is released, the operation characteristic of the shutter device is likely to change, since a vibration or shock acts in a nonuse state of the image sensing apparatus or after an elapse of a long term. When the vibration or shock is large, the latched state of the shutter blade is released, and the shutter blade may travel. In the arrangement which retains the shutter blade while stopping the shutter charge mechanism in the charged state, when the shutter blade is traveled in response to the shutter release operation, the shutter charge mechanism is required to be shifted from the charged state to the travel prepared state. For this reason, two operations are required upon shooting one frame, and a shooting time per frame is prolonged.
According to Japanese Patent Laid-Open No. 2000-089358 above, the shutter charge mechanism is always driven to the travel prepared state after the charge operation is completed. For this reason, an operation after the image sensing apparatus is left in a nonuse state for a long term becomes unstable, or the latched state of the shutter blade may be released and may travel upon acting a vibration or shock. Furthermore, in Japanese Patent No. 2765747, since the mirror is in the retracted state when the continuous shooting operation is stopped, the shutter has to be re-charged and the latch mechanism has to be retained by the retaining lever after the mirror returns.